area310dude

No snide!

It was meant as a compliment, you taught me a lot here and I really, really appreciate it.

If I was in Washington State, there is a beer and a pizza slice (with your name on it) I would like to give you!

Personally I couldn't find that much on the WWW about BLM and INT, so whatever you have to say on the subject, I would absorb like a sponge.  Especially with your tremendous background of knowledge and experience.

sorry for the misunderstanding.

It's okay to post a thesis here, professor!

Most us on this forum must certainly be amateurs like me, so only good can result from sharing the knowledge.

Maybe we could post some of this Block Learn info in a reference or 'sticky' part of the website.

I found some great website information that includes exactly what you said about Block Learn (BLM) and Integrator (INT) values:

http://carprogrammer.com/Z28/PCM/FAQ/How GM Electronic Fuel Injection Works.htm         (incomplete, but still helpful)

http://www.gnttype.org/techarea/faq/BLMINT.html         (about the Buick Regal, but still a very good and intuitive article)

I think maybe my earlier posting of the BLM and INT values doesn't help much because that is only just one 'Cell' situation where the Eldorado is idling at a fixed low RPM and low airflow.

The bottom line is that the rest of the 15 Cells (out of the total 16) are probably trying to correct a too-lean condition on the left bank of the engine, and not succeeding very well?

Please correct me if I'm saying anything incorrect.

I read in the FSM that 128 is the optimal value for codes ED36 thru ED39.

Since both the Left and Right B/Ls are below 128 (122 and 104 respectively) doesn't this indicate that both banks are too rich as sensed by the O2 sensors and they are trying to run lean?

Hi

I'm delaying the O-ring carburetor spray test a bit until the fuel injector additive in my gas tank burns down a bit more.

In the meantime could you tell me what the values below might indicate in relation to my E046 dilemma?

These are the diagnostic values just at idle.  I figure any extra evidence to share with you might help solve the puzzle.

ED36 Left Fuel Integrator   128

ED37 Right Fuel Integrator  128

ED38 Left Block Learn Fuel   122

ED 39 Right Block Learn Fuel  104

The numbers tend to jump around a bit with the exception of the 104 Right B/L number that stays steady.

Ok thanks, that sounds like an easy check, I'll try it.

I had another funny thought about the left/right bank fueling difference:

Since I haven't had a smog test yet to see if my NOx has reduced since cleaning the EGR system and replacing the EGR valve, could it be possible that the maybe the left bank is NOT TOO LEAN, but just fine?

Because maybe the right bank is burning TOO RICH, caused by a faulty injector on the right bank that is dripping extra fuel?

I included a picture of the old left and right O2 sensors below, can you conclude something from that?

And also, I should mention that the 'Service Engine Soon' light from the E046 code has always been intermittent, not constant, and always throwing the SES light when the engine is hot, usually when I get home after a long trip and the car is idling in the driveway.  The SES light is always off with E046 as a 'history' when I start it from a cold condition.  When the E046 code and 'Service Engine Soon' light comes on as 'current', I can also detect a faint rotten egg smell from the exhaust.  Isn't rotten egg smell an indicator of burning the fuel too rich?

Can we make some conclusions about these extra pieces of evidence I have provided?

Hi OldCadTech and Cadillac guys

It's been a long time since I last posted, but in that time I replaced both O2 sensors, the EGR valve, cleaned out the throttle body and EGR tubes, added fuel injector cleaner, but unfortunately the E046 'Left to Right Bank Fueling Difference' code came back just the same!

I think I did learn something that could be an important clue though.

When I removed the right bank O2 sensor, it was very black and sooty, but the old left bank O2 sensor was very clean looking, with no black stuff at all.  Obviously the right bank cylinders are combusting much richer than the lean left bank.

Maybe I should look for a non-working fuel injector(s) on the left bank, causing a lean condition?

Running too lean causes excessive NOx and smog test failures too, right?

Ok thanks, fellas.

I have a lot of work to do in the next week or two, I guess.

I will let you all know if I am able to get rid of the E046 code and also pass the smog test.

I think threads posted here are much more useful when we can read about how to successfully solve particular problems and trouble codes seen on the cars.

If the original posters just disappear at the end of a thread, we never know if a certain approach was successful or not.

Okay, I can see that a complete EGR system check is really essential to passing a smog test with low NOx.  I will definitely put that on the agenda, and check if the EGR solenoid is working well too.  As well as cleaning out the throttle body and the EGR tubes.

Since the previous vacuum gauge testing seemed to eliminate a fuel injector problem or a vacuum leak, should I also plan to replace the two O2 sensors in order to eliminate the E046 code and help improve my chances of passing the smog test?  Remember I was getting some extended lengths of time with zero (0) cross count readings on the right and left O2 sensors?

I got a lot of things on my plate with the old Eldorado I plan to take care of, but for the immediate future I think I had best try to pass that darned smog test first and make my car street-legal !

thanks very much for your great advice so far, OldCadTech

Hi, I am able to squeeze up the diaphrapgm on the EGR, but the engine keeps running with only a slight reduction in speed.

I'm thinking this EGR is no good and needs replacement (together with a new gasket).

At idle, there is some rapid waver that is plus or minus maybe 0.20 " Hg about the 18.5 " Hg reading.

The wavering is less than a quarter inch in either direction, in other words.

If that waver is acceptable, the Normal engine picture seems to be what I'm seeing.

it took a while to locate the right attachment for the big nipple # 91 (brake booster hose fitting) but I finally did it, and here are the results:

At a coolant temperature of 207 deg F, after 20 minutes of warming up

1) Vacuum at idle (650 rpm) was a fairly steady 18.5 " Hg

2) Vacuum at 2000 rpm was 21.5 " Hg

3) Vacuum with snapping throttle to about 2000 rpm caused the needle to fall to zero, then quickly jump up to 23 " Hg then go back to the idle vacuum of 18.5" Hg

Would connecting the vacuum gauge to the # 91 fitting also require a 'T' connection to tap into the line?

sorry for the rookie questions

Hi, I dug around in the garage and discovered I have a Sun brand vacuum gauge that looks very similar to the black one in your picture.

Is it okay to simply push the end of the rubber vacuum hose onto the nipple located at 102 ?

The hose isn't threaded, it looks like yours.

Sounds like a good comprehensive plan!

So it looks like I should start with checking the vacuum in the throttle body first, correct?

I'm almost sure the end of my vacuum gauge is threaded.

Is using a 'T' connection my only option?  How would I block off the open end of the T, please?

ok

'scuse my ignorance, I have a vacuum gauge in my toolbox, where would I attach it on the 4.9 liter?

And which vacuum condition would indicate a fuel injector problem?

great information all around!

i'm certainly learning something beyond what I got just from flipping through the service manual.

So to answer the previous question, the PCM is showing 'Closed Loop' running and the Auto icon is lit up.

Assuming that the "Likely causes of an E046" is ruled out (which I intend to double check) wouldn't the fault tree still indicate bad or lazy O2 sensors because both the right and left sensors had stretches of zero value cross counts during my test drives?

hello and thanks, I really appreciate you smart and experienced folks here on the forums.

I will double check the Auto light tonight.  I just realized there are two 'Auto' light icons on the A/C display!

In the attachment below, the Service Manual shows an 'Auto' icon on the left side that indicates Closed or Open Loop Mode status.

The right side has an 'Auto' icon that will say if the car is in Park/Neutral or not P/N, correct?

Which one should I be focusing on?

Doesn't Open or Closed also mean when the thermostat opens to let the hot coolant flow through the upper radiator hose too?

Could use some help/advice on diagnosing an E046 trouble code for a '92 Eldorado with the 4.9 liter engine. I also failed my last smog check because of excessive NOx, btw. I'm thinking the two things are related.

E046 is the the 'Left to Right Bank Fueling Difference' that will produce a Service Engine Soon light. My E046 is the single current code but the SES only comes on intermittently.

My due diligence of Googling other people's experience with the E046 on this and other forums has been a bit disappointing.

Many of the E046 complainers don't seem to use a Factory Service Manual for diagnosis, and most of the E046 threads I've seen have the guys replacing O2 sensors and fuel injection parts without really taking a more scientific approach (i.e. not throwing parts at the problem and hoping it will go away).  Apparently the O2 sensors can be bad and produce an E046 without spitting out a more O2-specific trouble code.

Anyway, the fault tree for E046 can be found on my attachment IMG_0379.jpg with some more info on E046 found in attachment IMG_0385.jpg

Going through the steps of the tree, I am witnessing the ED35 (Right O2 sensor cross count) bouncing around from 0 to a high of 34, while the ED34 (Left O2 sensor cross count) varying between 0 to a high of about 24. These values do not seem to linearly increase as the car accelerates or travels at a higher rate of speed. Even just idling in Park in my driveway can produce non-zero cross counts.

What should I do now?

I have seen previous posts with differing opinions, e.g. the actual numerical value doesn't matter, it's the frequency of the numbers changing, the 0 value is no good, a high number is better, etc. and so forth.

Some previous posters don't seem to have a really good grasp of what 'cross count' really means (me included).

I'm taking an educated guess that if the cross count reading is '5' as an example, this means the O2 sensor is dictating 5 changes per second from a rich to a lean burn. Is that correct?

So I have many more questions than answers, is there somebody out there that can help me with this dilemma?

I feel that just blindly replacing O2 sensors as historically been done might be my last resort otherwise.

Thanks, cadillac fellas.